Section III., 1914 



[83] Trans. R.S.C. 



The Nitrogen Compounds in Rain and Snow. 

 By Frank T. Shutt, M.A., F.R.S.C. 



(Read May 27, 1914). 



This investigation is a Canadian contribution towards an enquiry 

 that has been made in recent years, chiefly in Europe, but which is 

 now also being prosecuted in many other parts of the world, into the 

 amount and character of the nitrogen compounds contained m ram and 

 snow. The chief object in this research, at least from the agricultural 

 point of view, is to ascertain the weight per acre of these compounds 

 which may be furnished to the soil by the precipitation. The extent to 

 which the rain and snow may cleanse and filter the atmosphere is 

 undoubtedly an important factor of hygienic value and there are also 

 other features of scientific interest upon which information may be 

 obtained from the data. 



Agriculturally, this investigation is of peculiar interest in throwing 

 some light upon the important and fundamental problem of the up- 

 keep of soil fertility. Recent work in agricultural science has shown 

 that nitrogen is the dominant element of plant food, that, other 

 things being equal, vegetative growth is determined by the stores of 

 available nitrogenous food in the soil. Further, that losses of soil 

 nitrogen occur apart from abstraction through crop growth, through 

 tillage operations and though these may be minimized by due re- 

 gard to certain procedure, as by the adoption of a rational rotation, 

 which includes the growth of leguminous crops and the periodic lay- 

 ing down to grass, they must nevertheless be taken into consideration 

 in any study of the income and out-go of the soil's nitrogen. There 

 is also an important economic aspect to the question inasmuch as mtro- 

 ogen, in forms suitable for vegetative assimilation is the most costly 

 of all plant foods, It is obvious, therefore, that any phase of this 

 soil nitrogen problem is of peculiar interest and importance to 

 agriculture. 



The combined nitrogen of the atmosphere exists chiefly as am- 

 monia and secondarily as nitrates and nitrites and it is these com- 

 pounds which have been determined by observers in this research. 

 This source or origin is principally, but not solely, combustion. Un- 

 doubtedly the larger proportion arises from the consumption of 

 fuel, and thence the rain in the neighbourhood of large and man- 

 ufacturing towns is richer than that of the country, but the soil 



